Self-contained fluid management pump system for surgical procedures

ABSTRACT

A fluid management pump system (20) for applying an irrigation/distention solution to a surgical site. The system includes a pump (22) for forcing the solution through an inflow tube (28). A portable power pack (26) attached to the pup provides the energization current for actuating the pump. The solution is introduced into the surgical site from the inflow tube through a first cannula (30) across which there is a relatively small pressure drop. Fluid discharged from the surgical site is drained from the site through a second cannula (32) across which there is a low pressure drop. A hand controller (38) is attached to the inflow and outflow tubes. The hand controller contains a valve (46) for regulating fluid flow through the outflow tube. A pump control circuit (232) is also disposed in the hand controller. Based on the actuation of buttons (42, 44) mounted to the hand controller, the pump control circuit regulates the energization signal applied to the pump so as to regulate the rate at which solution is discharged from the pump.

FIELD OF THE INVENTION

This invention relates generally to fluid management pumps used forsurgical procedures. More particularly, this invention relates to aself-contained fluid management pump system that does not require asupplemental power supply or controller.

BACKGROUND OF THE INVENTION

Fluid management pump systems are employed during surgical procedures tointroduce sterile solution into surgical sites. For example, a fluidmanagement pump may be employed during an endoscopic surgical procedure.In endoscopic surgery, an endoscope is inserted into the body through asmall opening known as a portal. The endoscope is positioned at the sitewhere the surgical procedure is to be performed. The endoscope is asurgical instrument that provides a view of the portion of the body inwhich it is inserted. Other surgical instruments are placed in the bodythrough-other portals and are positioned at the surgical site. Thesurgeon views the surgical site through the endoscope in order todetermine how to manipulate the other surgical instruments. Thedevelopment of endoscopes and their companion surgical instruments hasmade it possible to perform minimally invasive surgery that eliminatesthe need to make large incisions to gain access to the surgical site. Anadvantage of performing endoscopic surgery is that, since the portionsof the body that are cut open are minimized, the portions of the bodythat need to heal are likewise reduced. Still another advantage ofendoscopic surgery is that it exposes less of the patient's internaltissues and organs to the open environment. This minimal opening of thepatient's body lessens the extent to which these internal tissues andorgans are exposed to infection.

The ability to perform endoscopic surgery is enhanced by the developmentof fluid management pumps. A fluid management pump pumps a sterilesolution into the enclosed portion of the body at which the endoscopicsurgical procedure is being performed. This pressure of this solutionexpands, distends, and separates the tissue at the surgical site so asto increase both the field of view of the site and the space availableto the surgeon for manipulating the instruments. One type of endoscopicsurgery in which fluid management pumps have proven especially useful isin arthroscopic surgery. In arthroscopic surgery, a specially designedendoscope, called an arthroscope, is employed to examine inter-bonejoints and the ligaments and muscles that connect the bones. A fluidmanagement pump is often employed in arthroscopic surgery to expand thespace between the bones and adjacent soft tissue in order to increasethe field in which the surgeon can perform the intended surgicalprocedure. Fluid management pumps are, during arthroscopic surgery, usedto increase the surgical view and working space around the joints thatform an elbow, a knee, a wrist or an ankle. During arthroscopic surgery,the pressure of the fluid introduced by the pump also reduces andcontains the internal bleeding at the surgical site. Moreover, fluidmanagement pumps are used in both endoscopic surgery and in othersurgical procedures to remove debris generated by the procedure.

The Applicant's U.S. Pat. No. 5,810,770, entitled FLUID MANAGEMENT PUMPSYSTEM FOR SURGICAL PROCEDURES, issued Sep. 22, 1998, and incorporatedherein by reference, discloses one conventional fluid management pumpsystem. This particular system includes a pump that is used to forcesterile solution to the surgical site. The pump is part of a tube setthat includes a inflow line through which the fluid flows from the pumpto the patient. The tube set also includes a second line, an outflowline, through which the fluid discharged from the surgical site isflowed to a collection container. The tube set has a third line forreceiving a fluid column from the surgical site. The head of the fluidcolumn in the third line is applied to a transducer which, in turn,generates a signal representative of the fluid pressure at the surgicalsite. This system also includes a control console to which the tube setis connected. In this particular system, the pressure transducer islocated in the control console. The control console converts the linevoltage into a signal suitable for energizing the pump. The controlconsole also includes a pair of solenoids, each one of which is in closeproximity with a separate one of the fluid inflow or outflow lines. Eachsolenoid regulates the open/closed state of a valve associated with aseparate one of the inflow or outflow conduits.

The control console also includes a number of switches that allows thesurgeon to regulate the fluid pressure and the rate of fluid flowthrough the surgical site. Based on the surgeon-set commands and thesensed fluid pressure at the surgical site, the control consoleselectively energizes the pump and opens and closes the inflow andoutflow conduits.

While the above described fluid management pump systems work reasonablywell, there are some disadvantages associated with their use. Inparticular, this type of system brings additional equipment, additionalclutter, to the surgical suite. Moreover, many current fluid managementsystems are designed so that the control switches that are actuated toestablish fluid flow rate and fluid pressure are mounted on the controlconsole. This means that, when a surgeon wants to reset these settings,he/she must either personally be divert attention from the instrumentsand the surgical site in order to depress the buttons on the controlconsole, or instruct an assistant to enter the new settings. There havebeen attempts to minimize this disruption by providing control consoleswith separate hand controllers. This type of controller is connected toits associated console by a cable. While this type of remote controllerworks reasonably well, it brings another device and a complementarycontrol line, both additional clutter, to the surgical suite. Moreover,as with any piece of reusable medical equipment, it is necessary tomaintain these consoles and even sometimes necessary to repair them.

The cannulae with which many current fluid management pump systems areused also have their own shortcomings which detract from the utility ofthese systems. These cannulae are the rigid members that are insertedinto the portals formed in the patient's body and that serve as theconduits through which the irrigating fluid is introduced into anddrained from the surgical site. In practice, it is often necessary toprovide three separate conduits to the associated tube set. A firstconduit serves as the flow path through which fluid is introduced intothe surgical site. A second conduit serves as the flow path throughwhich fluid is discharged from the surgical site. Finally, there is athird conduit over which a column of fluid is withdrawn from thesurgical site. This is fluid column that is applied to the complementarytransducer in order to determine the fluid pressure at the surgicalsite. These cannulae, in addition to providing fluid conduits, alsoserve as the conduits through which instruments such as theendoscope/arthroscope are seated at the surgical site.

The problem associated with many of these cannulae is that the fluidflowing through them undergoes a significant pressure drop. For example,studies have shown that in a system designed to apply approximately 1.8lit./min fluid flow, it is necessary to pump the fluid out of the pumpat a pressure of approximately 18 psig in order to maintain the fluid atthe surgical site at a constant pressure. Of this 18 psig of pressure,approximately 15 psig are lost in a pressure drop across one of thecannula. Thus, a significant amount of the power that is developed bythe pump is expended in order to simply force the fluid through thecannulae. This means that large amounts of energy are applied to thepump solely to overcome this cannula-centered pressure drop.Consequently, it has been necessary to provide current control consoleswith power converters that can deliver the large quantities of energyrequired by these pumps. The size of these power converters hascontributed to making current control consoles, heavy, bulky pieces ofequipment. Moreover, these power converters can significant amounts ofwaste heat.

Moreover, sometimes during a surgical procedure the outflow of fluidfrom the surgical site can be temporarily blocked. When this flow is soblocked, the pressure of the fluid output by the pump is not simply lostacross the cannula. Instead, the pressure of this fluid will be up atthe surgical site. If this pressure becomes too great, there is riskthat the patient's tissue may become damaged.

SUMMARY OF THE INVENTION

This invention relates to an improved fluid management pump system. Thefluid management pump system of this invention has a portable power packso as to eliminate the need to provide a bulky supplemental controlconsole. The controls used to regulate fluid flow and pressure are builtinto a hand controller that is mounted to the inflow and outflow tubes.The fluid management pump system of this invention also includes acannula through which the fluid flowing through undergoes a minimalpressure drop as it is flowed to or discharged from the surgical site.

BRIEF DESCRIPTION OF THE DRAWINGS

This invention is pointed out with particularity in the claims. Theabove and further features of the invention may be better understood byreference to the following description taken in conjunction with theaccompanying drawings in which:

FIG. 1 depicts the basic components of the fluid management pump systemof this invention;

FIG. 2 is a side view of the first low-loss cannula of this invention;

FIG. 3 is an exploded view of the cannula of FIG. 2;

FIG. 4 is a cross-sectional view of the proximal end of the cannula ofFIG. 2;

FIG. 5 is a cross sectional view of a horizontal slice of the cannula ofFIG. 2 taken along line 5--5 of FIG. 2;

FIG. 6 is an exploded view of the second low-loss cannula of thisinvention;

FIG. 7 is a cross sectional view of the cannula of FIG. 6;

FIG. 8 is an exploded view of the components forming the pump and powerpack;

FIG. 9 is a cross sectional view of the moving components of the pump;

FIG. 9A is an enlarged cross sectional of the upper end of the pumpdepicting the conduit through which fluid is discharged from the pump;

FIG. 10 is a cross sectional view of a horizontal slice through the pumptaken along line 10--10 of FIG. 9A;

FIG. 11 is an exploded view of the accumulator of this invention;

FIG. 12 is a cross sectional view of the accumulator;

FIG. 13 is an exploded view of the hand controller of this invention;

FIG. 14 is a cross sectional view of the chassis of the hand controllerdepicting the fluid paths through the hand controller;

FIG. 15 is a cross sectional of the hand controller depicting the flowpath of the irrigation/distention solution through the controller to thesurgical site;

FIG. 16 is a cross sectional view of the hand controller depicting theflow path of fluid discharged from the surgical site through thecontroller;

FIG. 17 is a cross sectional view depicting how the variable-pressurewater column from the surgical site is applied to the hand controller;

FIG. 18 is a block diagram of the sub-circuits internal the pump controlcircuit of this invention; and

FIG. 18A is a block diagram of an alternative circuit for supplyingenergization signals to the pump.

DETAILED DESCRIPTION

FIG. 1 depicts a fluid management system 20 of this invention that isemployed to supply a sterile distention solution to a surgical sitewithin a body and, more particularly, the joint capsule of a knee 21.The system 20 includes a pump 22 which receives solution from supplybags (not identified). The pump 22 is electrically driven and isenergized from a portable power pack 26 that is attached to and extendsbelow the pump. The pump 22 forces the solution downline towards thesurgical site through a flexible inflow tube 28. Initially, the fluidflows through an accumulator 29 that is in-line with the in flow tube28. The fluid is applied from inflow tube 28 to the surgical sitethrough a first low-loss cannula 30. Cannula 30, in addition to defininga conduit through which the fluid flows to the surgical site, defines aconduit in which an arthroscope, (not illustrated) is seated so that thearthroscope can be positioned at the surgical site. The fluid isdischarged from the surgical site through a second low-loss cannula 32.An outflow tube 34 is connected to the proximal end of cannula 32 forreceiving the discharged fluid. (Throughout this application "proximal"and "rearward" shall be understood to me away from the surgical site."Distal" and "forward" shall be understood to mean towards the surgicalsite.) The discharged fluid flows through the outflow tube 34 to anappropriate collection container 36. The inflow tube 28 and the outflowtube 34 are connected together starting at a point forward of theaccumulator 29.

A hand controller 38 is fitted over distal parallel sections of theinflow and outflow tubes 28 and 34, respectively. A cable 40 extendsfrom the pump 22 and power pack 26 to the hand controller 38. In thedepicted version of the invention, cable 40 is attached to the portionof inflow tube 28 that extends from pump 22. Hand controller 38 containsa circuit described hereinafter for regulating the energization signalapplied to the pump 22. Two buttons 42 and 44 allow the surgeon toregulate the energization signal applied to the pump 22. The handcontroller 38 also includes a flow control valve 46 for regulating fluidflow through outflow tube 34. By selective setting of energizationsignal applied to the pump 22 and the setting of the flow throughoutflow tube 34, the surgeon can control system 20 of this invention toregulate both the rate of fluid flow through the system and the fluidpressure at the surgical site.

In the depicted version of the invention, a flexible pressuremeasurement tube 48 extends from cannula 32 to the hand controller 38. Afluid column from the surgical site is applied to the hand controller 38through tube 48. A transducer, described hereinafter, internal to thehand controller 38 measures the pressure of the fluid column todetermine the fluid pressure at the surgical site. The circuit internalto the hand controller 38, based on a signal from the transducer,further regulates the actuation of the pump 22. In still more preferredversions of the invention, transducers internal to the hand controller38 also monitor the flow rate of the fluid through the inlet and outlettubes 28 and 34, respectively. The hand controller circuit also usesthis flow rate data to further regulate the energization of pump 22.

The first low-loss cannula 30 is now described by initial reference toFIGS. 2-4. Cannula 30 includes an elongated sleeve-like shaft 52. Theproximal end of shaft 52 is seated in the distal end of a hub 54. Thehub 54 has a disk-like base 56 which functions as the distal bottom endof the hub. A skeletal frame 58 extends rearward from base 56. Frame 58has a generally circular cross sectional profile. Collectively, base 56and frame 58 are shaped to define a bore 60 that extends axially throughthe hub 54. Shaft 52 is permanently mounted in the distal end of bore60. A body 62 extends over frame 58 and rests against the rearwardfacing surface of base 56. Body 62, as described hereinafter, is thecomponent of the cannula 30 through which fluid transits. Two O-rings 64that extend around frame 58 provide a liquid tight seal between theframe and the body 62. A first one of the O-rings 64 is locatedimmediately above the forward-facing surface of hub base 56. A secondone of the O-rings 64 extends around the proximal end of a bore 66 thatextends axially through body 62. Annular flanges 68 that are part of hubframe 58 hold O-rings 64 in position.

A lock base 70 is fitted over the proximal end of hub frame 58 thatextends rearward of body 62. A pin 72 extends through the lock base 70and seats in a small bore in the hub frame 58 to ensure that the lockbase is properly positioned relative to the hub 54, (frame bore notidentified). Set screws 74 secure the lock base 70 to the hub frame 58.A lock tab 76 is slidably mounted in a notch 78 formed in the forwardend of the lock base 70. A circular scope piece 80 is secured to thelock base 70 over the lock tab 76. A lock O-ring 82 is fitted around thescope piece 80. Collectively, lock base 70, lock tab 76, scope piece 80and lock O-ring 82 form an assembly for releasably holding anendoscope/arthroscope to cannula 30. A more complete discussion of howthis assembly functions is found in the Assignee's U.S. Pat. No.5,456,673, entitled, LOCKING CANNULA FOR ENDOSCOPIC SURGERY, issued Oct.10, 1995, which is incorporated herein by reference.

The structure of body 62 of cannula 30 is now described in greaterdetail by reference to FIGS. 3-5. Body 62 is formed so as to have anopening 84 in which a hose barb 86 is seated. The hose barb 86 is ashort tubular member to which the associated fluid tube, here inflowtube 28, is attached. Cannula body 62 is formed so that opening 84 isoffset from the longitudinal axis that extends through shaft 52 and hubbore 60. More particularly, the body 62 is formed so that the crosssectional space subtended by opening 84 does not subtend the crosssectional space subtended by hub bore 60. Cannula body 62 is furtherformed so as to have a center space 88 with a circular cross sectionalprofile that completely surrounds and is in fluid communication with hubbore 60. Center space 88 is the space internal to the body 60 with whichopening 84 is in direct fluid communication. Cannula body 62 is furtherformed so that inner wall thereof that defines the outer perimeter ofcenter space 88 has is curved. The cannula body 62 is shaped so thatcenter space 88 has a diameter equal to the sum of the diameter of thehub bore 60 and the diameter across opening 84. Thus, thecross-sectional flow path through opening 84 and in center space 88around hub bore 60 are essentially identical.

The hub frame 58 is formed so as to have two diametrically opposed,spaced apart legs 90 that extend through body center space 88. Each leg90 extends from the flange 68 that is immediate rearward relative todistal O-ring 64 to the flange 68 that is immediately forward ofproximal O-ring 64. When fluid is flowing through cannula 30, it flowsbetween body center space 88 and hub bore 60/shaft 52 through the gapsbetween legs 90.

FIGS. 6 and 7 illustrate the structure of the second low-loss cannula 32of this invention. Cannula 32 includes an elongated hollow shaft 94.Shaft 94 is formed to have a distal end with an inwardly directed taper96. The shaft 94 is further formed to have a single opening 98 at thedistal end thereof. Owing to taper 96, opening 98 has a diameter lessthan the diameter of the inside wall of shaft 94. A number of auxiliaryopenings 102 are formed in the distal end of shaft 94 immediatelyrearward of tapered section 96. Openings 98 and 102 collectively form acolander that allow significant fluid flow from the surgical site intoshaft 94 while preventing medium sized debris from becoming entrained inthis fluid flow.

A head 104 is fitted over the proximal end of shaft 94, the end of theshaft located above the portal in which the shaft is seated. Head 104 isformed so as to have a proximal end that is shaped to function as a hosebarb 106 to which the outflow tube 34 is connected. A through bore 108extends axially through head 104 from hose barb 106 to the distal end ofthe head. The proximal end of shaft 94 is seated in a counterbore 110integral with bore 108 in the distal end of the head 104.

Cannula 32 also includes a sample tube 112 that is welded or otherwisepermanently secured to the inside wall of shaft 94. Sample tube 112 isof relatively small diameter. For example, if shaft 94 has an innerdiameter of approximately 0.200 inches, sample tube 112 has an outsidediameter of approximately 0.040 inches. The distal end of sample tube112 is located immediately rearward of openings 102 in shaft 94. Theproximal end of sample tube 112 extends rearward out of shaft 94. Theportion of the sample tube 112 that extends rearward of shaft 94 isseated in an auxiliary bore 114 formed in head 104 that is parallel withand spaced from through bore 108. More specifically, auxiliary bore 114extends rearward from a stepped surface between through bore 108 andcounterbore 110. Head 104 is provided with a sensing barb 116 that is influid communication with sample tube 112 through auxiliary bore 114.Sensing barb 116 is a hose barb designed to receive pressure measurementtube 48. The sensing barb 116 is fitted in a hole 118 formed in the sideof head 104 that is in fluid communication with auxiliary bore 114. Moreparticularly, head 104 is formed so that hole 118 meets auxiliary bore114 at an angle of approximately 45°.

The pump 22 and power pack 26 are now initially described by referenceto FIGS. 1 and 8. Pump 22 includes a chassis 122 that contains the motor124 and other moving components of the pump. Power pack 26 includes ashell 126 in which the energy-providing batteries 128 for the system 20of this invention are housed. In the depicted version of the invention,shell 126 is shaped to hold two rows four series-connected batteries126. Two conically shaped coil springs 130 are seated in the base ofshell 126. Springs 130 urge the rows of batteries towards chassis 122 sothat the lead battery of each row physically abuts an associated contactmounted in the chassis. The springs 130 are connected together so as toestablish a series connection between the rows of batteries 126.Integrally formed with shell 126 is a flat, oval-shaped reinforcing ring133 that extends around the open end of the shell. A flexible tab 134extends downwardly and outwardly from the opposed straight sections ofreinforcing ring 133. A shell cap 136 is fitted over the open end ofshell 126 and the batteries 126 contained therein. Shell cap 136 isformed with a base that has opposed openings 138. Tabs 134 extendthrough openings 138 so as to hold cap 136 to the shell 126. Shell cap136 is form with a top that has two through holes 140. Holes 140 serveas access ports through which the contacts extend so that the contactscan abut batteries 128.

Pump chassis 122 (described by reference to FIGS. 9, 9A and 10) has alower frusto-conical section 142 in which the motor 124 is seated.Integrally formed with and located above frusto-conical section 142,chassis 122 is shaped to have a constant diameter section 144. Theirrigation/distention solution is gravity flowed into the constantdiameter section 144 of the chassis and forced out of the section by thepumping action. A bottom cap 146 is snap fitted to the open bottom endof the chassis frusto-conical section 142. The bottom cap is formed witha downwardly directed, oval shaped, open ended sleeve 148. Sleeve 148 isshaped to receive shell cap 136 and the upper end of shell 126. Theinner surface of sleeve 148 is formed with two opposed notches (147).The outer ends of shell tabs 134 extend through cap holes 140 and seatin the sleeve notches so as to hold the power pack 26 to the chassis122. The exposed ends of tabs 134 can be depressed inwardly so that thetabs retract away from the notches. The separation of the tabs 134 fromthe back cap sleeve 148 allows the power pack 26 to be separated fromthe pump 22. Bottom cap 146 is formed to have a center-located, upwardlyextending, tube-shaped mounting post 149. Motor 124 is seated onmounting post 149.

Three flat contacts 150, 152 and 154 are seated in bottom cap 146.Contacts 150 and 152 are seated in openings 156 formed in the base ofthe bottom cap 146 and are the contacts that physically abut thebatteries 128. The third contact 154 extends from the positive terminalof the motor 124 (terminal not illustrated) to contact 150, the contactassociated with the positive terminal of the batteries 128. Alsodepicted in FIG. 8 is a conductive connector 158. Connector 158 providesa conducive path between the negative terminal of the motor 124 and awire that extends to hand controller 38 (motor terminal and wire notillustrated).

Pump chassis 122 is formed to have a flat, ring shaped lip 160 thatextends inwardly from the inner wall of the chassis along the plane atwhich the constant diameter section 144 extends from frusto-conicalsection 142. Chassis 122 is further formed to have a tubular web 162that extends upwardly from the inner surface of lip 160. The space abovelip 160 within web 162 functions as the pump chamber 164 for the pump22.

When the pump 22 is assembled, the top surface of the motor 124 pressesagainst the rearwardly directed face of lip 160. Motor 124 has arotating shaft 168. Shaft 168 extends through the circular openingdefined by the inner perimeter of lip 160 into pump chamber 164. Theshaft 168 extends through a lip seal 170 located in the base of the pumpchamber 164 and that rests against the inner portions of lip 160. Thering-shaped hoop 172 formed of plastic extends around the shaft 168 andis pressed against the outer portion of the forward-directed face of lipseal 170. Hoop 172 is compression fitted against web 162 and holds lipseal 170 in position.

As best seen by FIGS. 9A and 10, pump chassis 122 is further formed tohave an outlet conduit 174 that expends from pump chamber 164. Thechassis 122 is shaped so that conduit 174 extends from an opening 176 inweb 162 along an axis that is offset from the axis of motor shaft 168.The plastic forming conduit 174 is shaped so that, downstream fromopening 176, the conduit curves downwardly so that the distal endthereof is parallel to the axis of the motor shaft 168. In order to formthe conduit 174 it will be noted that the outside of the chassis 122 hasa raised rib 178 that extends from approximately the mid-level of thechassis constant diameter section 144 downwardly along the completelength of the frusto-conical section 142. Chassis is further formed sothat the downstream section of conduit 174 that runs parallel to themotor shaft 168 has a diameter that is greater than the diameter of theportion of the conduit adjacent the pump chamber 164. The increaseddiameter of this section of the conduit 174 facilitates the seating ofthe proximal end of the inflow tube 28 in this portion of the conduit.

While not show, it should be understood that the pump chassis 122 isfurther formed with a small opening that opens into conduit 174 adjacentthe distal bottom open end of the conduit. This opening is the openingthrough which cable 40 extends. Downline from this opening, cable 40 issecured by an adhesive or other suitable means to the outer surface ofinflow tube 28.

An impeller 180 is mounted over the free end of motor shaft 168 in pumpchamber 164. The impeller 180 is shaped to have vanes 182 that areforward swept. That is, vanes 182 have a curved profile such that asthey extend outwardly from the center of the impeller, they curve in thedirection of rotation of the impeller 180. It will be observed that theimpeller 180 is spaced inwardly from the adjacent chassis web 162 and isspaced above the top of hoop 172. This arrangement serves to minimizethe friction that develops when the pump 20 is actuated.

A circular top cap 184 is compression fitted over the top of the pumpchassis 122 and the pump chamber 164. Top cap 184 has a base 186 that isseated in the open end of chassis constant diameter section 144. Anannular side wall 188 extends upwardly from base 186 and presses againstthe inner surface of the chassis constant diameter section 144. Anoutwardly directed flange 190 extends perpendicularly away from the topof side wall 188. Flange 190 limits the downward movement of top cap 184towards chassis 122. An inlet sleeve 192 expends upwardly from base 186above side wall 188. The sleeve barb 192 is centered over center axis ofthe impeller 180. Inlet sleeve 192 is formed with two openings so thatsupply lines 194 (FIG. 1) from two supply bags can be connected to thepump 22. Inlet spikes 195 are fitted to the ends of supply lines 194 forconnecting the proximal ends of the lines to the supply bags.

The structure of the accumulator 29 is now described by reference toFIGS. 1, 11 and 12. The body of the accumulator is an elastic, elongatedtubular balloon 198. The balloon 198 is shaped to have an inlet opening199 at one end through which solution flows into the balloon and anoutlet opening 200 at the opposed end through which solution flows fromthe balloon. Balloon 198 is formed of an elastomer such as low-durometersilicon rubber, so that the balloon can both expand and, when thesolution therein can flow, contract.

Inflow and outflow connectors 202 and 204, respectively, are seated inthe opposed open ends of the balloon 198. Connectors 202 and 204 areidentical in shape. Each connector 202 and 204 has a tubular body 206 inwhich end sections of inflow tube 28 are seated. A tube-like sleeve 208extends from each body 206. Sleeves 208 have both inner and outerdiameters that are less than the diameters of the associated bodies 206.Sleeve 208 of inflow connector 202 is seated in the inlet opening 199.Inflow connector 202 thus serves as the component that connects theportion of inflow tube 28 that extends from the pump 22 to theaccumulator 29. Sleeve 208 of outflow connector 204 is seated in outletopening 200. Outflow connector 204 thus serves as the component thatconnects the portion of the inflow tube 28 that extends downline fromthe accumulator 29 to the hand controller 38.

A pair of diametrically opposed fingers 210 extend from each connectorsleeve 208. A circular web 212 is attached to the end of each opposedpair of fingers 210 and held in place by the fingers. The openingdefined by each web 212 is coaxial with the bores that extend throughthe associated connector body 206 and sleeve 208, (openings and boresnot identified). A plunger 214 is mounted to inflow connector 202.Plunger 214 has a stem 216 that extends through the opening in theassociated connector web 212. Integral with the stem 216, the plunger214 has a conical shaped head 218 that is directed towards the open endof inflow connector sleeve 208. A spring 220 is fitted around stem 216.Spring 220 extends between web 212 and the opposed surface of theplunger head 218 so as to bias the plunger towards sleeve 208. Spring220 has a biasing force that holds the plunger 218 against the inletconnector sleeve 208 when there is no fluid flow from the pump 22 andthat allows the head to retract away from the sleeve when there isanything more than a nominal fluid flow from the pump.

The hand controller 38, as seen by FIG. 13, includes a chassis 224 thatserves as the base of the controller and a key pad 226 that extends overthe open top of the chassis. A printed wiring board 228 is mountedinside key pad 226. Printed wiring board 228 contains the transducersthat monitor fluid flow through the hand controller 38 and the pressureof the fluid at the surgical site. Manually-actuated, momentarily-onswitches 230 are mounted to the printed wiring board 228 to allow thesurgeon to regulate operation of the fluid management pump system 20 ofthis invention. For example, in some versions of the invention switches230 are membrane-type switches. Also mounted to the printed wiring boardis a control circuit 232 that receives signals from transducers andswitches 230. Based on these inputs, control circuit 232 regulates theactuation of pump 22 by regulating the application of energizationsignals to the pump. In some versions of the invention, control circuit232 may be a single one of or pair of application specific integratedcircuits (ASICs).

The flow control valve 46 is mounted to hand controller chassis 224. Thevalve 46 has a body 234 that is seated in bore 236 formed in chassis224. The body 234 has a through hole 237 through which fluid canselectively flow. Seals 240, in the form of O-rings, are seated inannular grooves 242 formed in the opposed ends of valve body 234. Theseals 240 provide a liquid tight barrier around the valve body 234.

A small post 238 extends downwardly from the base of valve body 234. Thepost 238 is snap fitted for rotation in a complementary open endedmounting boss 239 (FIG. 16) mounted to the printed wiring board 228.Flow control valve 46 also has a control lever 244 that is integrallyformed with the valve body 234. A surgeon sets the rotational positionof the valve body 234 by moving the control lever 244 in order toregulate the flow of fluid from the surgical site. A rib 245, shown incross section in FIG. 17, is integrally formed on the exposed face ofchassis 224 adjacent the control lever 244. Rib 245 limits the movementof the control lever 244 to cause a like limitation of the rotation ofvalve body 234.

The handpiece chassis 224, now described by reference to FIGS. 13 and14, is shaped to have two rigid internal tubes 246 and 248 that extendthrough the chassis. Tube 246 functions as the conduit through whichirrigation/distention solution flows through the hand controller 38 tothe surgical site. Tube 248 functions as the conduit through which thefluid discharged from the surgical site drains through the handcontroller 38 to container 36.

Tubes 246 and 248 are formed so that the opposed ends thereof have theapproximately same constant diameter inner wall. Tubes 246 and 248 arefurther formed so that their center sections 250 and 252, respectively,have a venturi profile. Thus, the middle of each tube center section 250and 252 is the smallest diameter portion of the conduit through thetube. The purpose of this construction will be obtained hereinafter.Tube 246 is further formed to have receiving sleeves 254 that arelocated at the opposed ends of the tube. Tube 248 is further formed tohave receiving sleeves 256 that are located at the opposed ends of thetube. Each receiving sleeve 254 and 256 extends a short distance outsideof the adjacent end of the handpiece chassis 224. Receiving sleeves 254and 256 have inner diameters that are dimensioned slightly large thanthat of the adjacent inside diameters of the associated tubes 246 and248, respectively. The ends of the sections of the inflow tube 28 thatare coupled to controller tube 246 are fitted in receiving sleeves 254.The end of the sections of the outflow tube 34 that are coupled tocontroller tube 248 are fitted in receiving sleeves 256.

Controller tube 248, is further formed so as to have a receiving space258 which is located in the controller 38 so as to be distal relative tothe venturi-profiled center section 252. Receiving space 258 is shapedto accept the body 234 of flow control valve 46. Thus, by setting therotational position of valve body 234 in the receiving space 258, valvebody through hole 237 is selectively moved in and out registration withthe center of tube 248. This action regulates the fluid flow throughhand controller 38 and from the surgical site.

Handpiece chassis 224 is further formed to have a rigid measurementconduit 260. In the depicted version of the invention, measurementconduit 260 extends out of the end of the chassis directed towards thepatient and is located between controller tubes 246 and 248. Themeasurement conduit 260 is formed so that the end of the conduit locatedinside chassis 224 is closed. The proximal end of pressure measurementtube 48 is fitted in the open end of measurement conduit 260.

The handpiece chassis 224 is further formed with an tube-shapedelectrical conduit 262. In FIG. 14, conduit 262 is depicted as beingaxially aligned with measurement conduit 260 and shown extending out ofthe proximal end of the chassis. Conduit 262 is the member through whichcable 40 extends into the hand controller 38. Not identified are thewires within cable 40 that are connected to the control circuit 232through contacts on printed wiring board 228.

Handpiece chassis 224 is further formed so as have an outer wall 264that serves as the outer side wall of the handpiece controller 38.Chassis 224 also has an inner wall 266 that is spaced inwardly fromouter wall 264 and that, like inner wall 264, extends upwardly from thebase of the chassis. The outer and inner walls 264 and 266,respectively, are the portion of the chassis through which receivingsleeves 254 and 256, measurement conduit 260 and electrical conduit 262extend.

Controller key pad 226 has a flat base 270. A solid lip 272 extendsperpendicularly around base 270 and is spaced inwardly a slight distancefrom the outer perimeter of the base. When the hand controller 38 isassembled, key pad lip 272 is seated in the interstitial space betweenouter and inner walls 264 and 266, respectively, of chassis 224.

The inner surface of key pad base 270 is the surface to which theprinted wiring board 228 is mounted. Mounted in separate holes 274forming in the base 270 are buttons 42 and 44. Each button 42 and 44,when depressed, closes a separate one of the membrane switches 230mounted on the adjacent outer surface of printed wiring board 228.

Five transducers 276 are mounted to the printed wiring board 228 formonitoring the pressure of the fluids flowing through and to handcontroller 38. Each transducer 276 extends downwardly from the printedwiring board towards the chassis 224. As seen in FIG. 15, chassis tube246 has two ports 278 through which two of the transducers 276 extendinto the center of tube 246. Specifically, one of the transducers 276extends into the distal constant diameter section of tube 246. Thesecond transducer 276 extends into the smallest diameter portion of thetube center section 250. Similarly, as shown in FIG. 16, chassis tube248 has two ports 280 through which two of the other transducers 276extend. In tube 248 a first one of the transducers 276 is located in thesmallest diameter portion of the tube center section 252. The remainingtransducer 276 is located in the constant diameter section of tube 248that is located downstream and proximal from center section 252.

The transducers 276 in chassis tubes 246 and 248 are employed to providean inferential measurement of flow through the tubes. Specifically, forversions of the invention employing these transducer 276, the followinginformation is thus known for each tube: the ratio of the area of thetube flow paths between the wide and narrow sections of the tube; andthe ratio of the pressure of the fluid flow between the wide and narrowsections of the tube. Based on this data, the rate of fluid flow througheach tube 246 and 248 can be calculated.

As depicted in FIG. 17, the fifth transducer 276 is mounted in a port282 formed in measurement conduit 260. This transducer 276 is locatedadjacent the closed end of conduit 260. The fifth transducer 276measures the fluid pressure of the fluid column that is applied to thehand controller 38 from the surgical site through pressure measurementtube 48.

A basic block diagram of the sub-circuits internal to control circuit232 is shown in FIG. 18. Circuit 232 includes a main controller 290 towhich switches 230 are connected. Main controller 290, primarily basedon the power level the surgeon sets by selectively closing the switches230, establishes the level of the power that is to be applied to themotor 124.

Main controller 290 produces a signal representative of the power to beapplied to the motor 124. This signal is applied to a power regulator292. The power regulator 292, based on the signal from main controller290, regulates the power that is applied from power pack 26 to the motor124. In the version of the invention depicted in FIG. 18, powerregulator 292 performs pulse modulation of a constant voltage signalthat is applied to the motor 124. This pulse modulation is performed byselectively tieing the motor 124 to the ground plane internal to thecontrol circuit 232. The connecting of the motor 124 to groundeffectively closes the circuit over which power is applied to the motor.

In an alternative version of the invention depicted in FIG. 18A, thepower regulator is a programmable DC/DC converter 292a. This convertorprovides a constant, variable voltage level power signal to the motor124.

Internal to circuit 232 there are also inflow and outflow flow rateprocessors 294 and 296, respectively. These processors 294 and 296,which are constructed of analog and/or digital circuit elements,generate signals representative of the rate of flow through chassistubes 246 and 248, respectively. The inflow processor 294 receives asinput signals the pressure signals from transducers 276 integral withtube 246. The outflow processor 296 receives as input signals thepressure signals from the transducers 276 mounted to tube 248. Each flowrate processor 294 and 296 generates signals representative of the rateof fluid flow through the tube with which the processor is associated.These flow rate signals are applied to the main controller 290.

The signal produced by transducer 276 mounted in measurement conduit 260is applied directly to the main controller 290. It should be understoodthat the algorithms that main controller 290 employs to regulate theenergization of the pump motor 124 are proportional integraldifferential algorithms. The algorithms are proportional in the sensethat changes in the measured fluid state result in a change in the powerlevel of the pump established by the motor controller 290. Integralforms of these signals are used so as to eliminate any short noisespikes in the state signals. Differentiated versions of these integratedsignals are employed in that so that main controller 290 not onlycorrects for changes in the sensed state(s) of the measure fluid, itfurther corrects based on the rate of change of the sensed fluidstate(s).

Control circuit 232 further includes a sub-circuit 298 for measuring thecurrent out of the power pack 26 and the voltage across the power pack.Sub-circuit 298 produces output signals representative of these changesstates of the output signal from the power pack 26. The signals producedby sub-circuit 298 are applied to the main controller 290.

The fluid management pump system 20 of this invention provides anirrigation/distention solution to a surgical site. Pump 22 provides thepumping force for forcing the fluid from the supply bags 24 through theinflow tube 28 and cannula 30 to the surgical site. The hand controller38 regulates the energization of the pump 22 so as to control the rateat which the fluid is forced to the surgical site.

The surgeon sets both the rate at which the solution is followed to thesite and the fluid pressure at the site by depressing buttons 42 and 44and setting flow control valve 46. Specifically, the surgeonraises/lowers the fluid pressure at the surgical site by depressingbutton 42 or 44 to raise/lower the power applied to the motor 124 whileholding the setting of fluid control valve 46 constant. Alternatively,the surgeon increases or decreases the fluid flow rate through thesurgical site by resetting the position of fluid control valve 46without manually changing the power settings by depressing button 42 or44. In this way, independent control of flow rate and pressure isachieved.

In versions of the invention in which transducers 276 are installed inthe hand controller 38, the signals representative of the fluid stategenerated by the transducers are also used to regulate the applicationof power to the pump 22. Specifically, if the transducer 276 employed tomeasure fluid pressure at the surgical site indicates that there hasbeen a drop or a rise in fluid pressure, main controller 290 generates acontrol signal to cause, respectively, an increase or a decrease inpower to the pump.

If the transducers 276 associated with the chassis tube 246 throughwhich the fluid is introduced into the surgical site indicate a drop influid flow rate, the main controller 290 increases the power to the pump22. Executing this adjustment maintains the fluid pressure at thesurgical site. If the transducers 276 associated with the chassis tube248 through which fluid flows from the surgical site indicate that thereis a drop in fluid flow, the main controller 290 causes the power to thepump to be decreased. This adjustment also serves to maintain the fluidpressure at the surgical site.

In versions of the invention in which control circuit 232 is providedwith power pack state monitoring sub-circuit 298, main controller 290further adjusts the power applied to the pump 22 as a function of thestate of the power pack 26. Specifically, if the current produced by thepower pack 26 falls, motor controller 290 resets the power applied tothe motor 124 to increase the voltage or increase the percent on-dutycycle for the energization signal. Motor controller 290 also isconfigured to adjust the energization signal applied to motor 124 basedon the state of the voltage across the power pack. If the power packvoltage falls and the power regulator 292 is a pulse width signalcontroller, motor controller 290 causes regulator to increase theon-duty cycle for the energization signal. If, however, control circuit232 includes the DC/DC converter 292a, motor controller 290 resets theregular to hold the level of the DC energization signal constant.

Accumulator 29 dampens the flow of solution to the surgical site.Usually, when the pump 22 is actuated, the force of solution forceddownstream by the pump is sufficient to hold plunger 214 open. Thus, atthese times, solution simply flows through the accumulator 29 downstreamthrough the hand controller 38 and cannula 30 to the surgical site.However, there may be times when the pressure in the joint capsuledrastically increases. Once this happens, there may be a back up offluid in the inflow tube 28. If this back up occurs, the back pressurecauses plunge 214 to move towards the inward connector sleeve 208. Thisaction prevents the fluid in the accumulator 29 from continuing to backflow. Thus, the back flowing fluid fills the balloon 198 and the balloonthus expands to receive this fluid. The transducer 276 employed tomonitor fluid pressure at the surgical site will, while this action istaking place, generate a signal indicating that this pressure rise isoccurring. The main controller 290, based on this signal, reduces orshuts off the power to the pump 22.

Owing to the elastic properties of the accumulator balloon 198, once theback flow ceases, the balloon will contract. The contraction forces thefluid in the balloon 198 out through outflow connector 204 anddownstream towards the surgical site. This fluid flow thus serves, forat least a short time period, to maintain the fluid pressure at thesurgical site. Once the balloon 198 retracts to its normal size, thefluid pressure at the surgical site may start to fall. This pressuredrop is measured by the transducer 276 connected to the pressuremeasurement tube 48. Upon receiving the signal indicating that thispressure drop has occurred, main controller 290 increases power to thepump 22. The fluid discharged from the pump 22 forces the plunger 214back to the open state.

The fluid management pump system 20 of this invention is designed sothat the power that energizes the pump 22 comes from a portable pack 26that is integrally attached to the pump. Thus, the system of thisinvention does not employ a separate console for converting line voltageinto a signal suitable for energizing the pump. Thus, the systemeliminates the need to bring a separate control console into anoperating room where such can device adds to the overall clutter.Moreover, unlike systems that include these control consoles, theenergization of this system is not dependent on the availability of awall-mounted power outlet.

A further benefit of this construction of the invention is that the pumpsystem, from the power pack 26 to the hand controller 38 can beassembled as a single unit and sterilized at the point of manufacture.One using this system does not have to sterilize a stand along controlconsole between uses of the system.

Moreover, still another feature of pump system 20 is that handcontroller 38 and associated cable 40 are integral with the inflow andoutflow tubes 28 and 34, respectively, through which fluid flows to andfrom the surgical site. A benefit of this construction is that it doesnot bring a separate control unit, additional clutter into closeproximity to the patient. Moreover, since the hand controller 38 isalways attached to the tubes 28 and 34, the surgeon always knows wherethis unit is. Thus, the time spent reaching for this unit in order toadjust fluid flow rates or pressures is held to a minimum.

Still another feature of the system 20 of this invention is that bothcannulae 30 and 32 are designed to minimize the pressure drop of fluidthrough them. Fluid entering cannula 30 through hose barb 82 and opening84 initially flows in a circular path around the shaft of the endoscopeextending through body center space 88. Owing to the curved walls ofcannula body 62 that form center space 88 and the circular profile ofthe body, this flow develops very little turbulence. Due to thecontinued introduction of fluid into space, the flow does develop anspiral pattern. Thus, the fluid undergoes a gradual tangential, downwardturn. Eventually, the fluid does flow down the cannula shaft 52 in theannular space between the inner wall of the shaft and the outer wall ofthe endoscope.

Since minimal turbulence develops in the flow through the cannula body62 and cross sectional flow path through body opening 84 and aroundcenter space 88 are substantially identical, there is only a smallpressure drop across cannula 30 of this invention. For example,measurements have shown that when there is 1.8 lit/min fluid flow ratethrough the cannula 30, the pressure drop is only between 0.5 and 1.5psig. An advantage of this low pressure drop is that it minimizes thepumping power required to force liquid through the cannula. Theminimization of this pumping force reduces the amount of current thatneeds to provided to the pump in order to supply the fluid needed toperform a surgical procedure. This reduction in the amount of currentthat needs to be supplied to the pump 22 makes it possible for theportable power pack 26 to be able to supply current to the pump for anappreciable length of time.

Cannula 32 is also designed to minimize the pressure drop of the fluidflowing through it. Specifically, fluid flows through shaft 94 head bore108 and hose barb 106 of cannula 32 along a linear path of travel.Moreover, the flow path through has a cross section area that isessentially constant along the length of the cannula. Also, pressuresampling tube 112 is positioned to be located around the outer perimeterof the flow through space in shaft 94. This arrangement minimizes thedevelopment of turbulence as fluid flows around the end of the samplingtube 112. Collectively, these features ensure that for a fluid flowingat a rate of approximately 1.8 lit/min through cannula 32, the pressuredrop is less than 1.5 psig.

Still another benefit of cannula 32 is that it is a relatively simpleand economic task to permanently weld or otherwise secure the pressuresampling tube 112 to the inside wall of shaft 94. Thus, cannula 32 inaddition to serving as low pressure loss conduit for removing fluid from(or introducing fluid into the surgical site) and for extracting a watercolumn for measurement purposes, is relatively inexpensive tomanufacture.

There is another benefit associated with the low loss cannulae 30 and32. Since significant quantities of pressure do not have to be expendedforcing fluid through the cannulae 30 and 32, the pump 22 need only bedesigned to provide a fluid flow that is at a relatively small pressure.For example, in versions of the invention designed to provide fluid at aflow rate of 1.8 lit/min, the pump 22 may be designed to discharge thisfluid at a pressure of 10 psig or less. In more preferred versions ofthe invention, the pump designed to output fluid at the above rate willdo so at a maximum pressure of 5 psig. An advantage of this constructionof the invention is that, in the event the outflow of fluid from thesurgical site is blocked, there is little likelihood that the pump 22will cause a large build up of fluid pressure that could potentiallyinjure the patient. This benefit of the invention is especially usefulin versions of the system 20 that, as discussed below, are not providedwith a transducer for measuring fluid pressure at the surgical site.

Still another feature of the system 20 of this invention is that thevanes 182 of the impeller are forward swept. Consequently, when thespeed of the pump 22 is increased to increase fluid outflow, thepressure output of the fluid likewise increases.

The pump chassis 122 of this invention is constructed so that integrallyformed with the chassis is conduit 174 which is shaped to have a 90°curve. Thus, the solution is discharged from the chassis along a vectorthat is downwardly directed and parallel to the longitudinal axis of thepump 22. This arrangement minimizes the extent to which the inflow tube28, upon exiting the pump 22, simply sticks out of the pump. Moreover,since the conduit 174 is formed integrally with the chassis, thisstructure eliminates the need to provide an additional piece of rigidtubing in order to cause this desired change in flow path. Thus, thepump 22 of this invention has a space efficient and aestheticallypleasing fluid flow path that does not significantly add to the cost ofproducing the pump.

The accumulator 29 serves as a reservoir for fluid forced through pumpwhen a condition exists in which a back flow could possible. This fluidis stored in the accumulator 29 until this conditions ceases to bepresent. Once the back flow condition is over, the accumulator forcesthe fluid downstream to the surgical site. Thus, the accumulator 29stores the energy previously generated by the pump and releases thisenergy when needed. The accumulator 29 thus serves to further reduce theamount of energy that needs to be applied to the pump 22 in order tokeep this system 20 in operation.

Moreover, even during times when there is no back flow back into theaccumulator 29, its body expands and contracts so as with variations influid flow so as to minimize drastic pressure changes at the surgicalsite.

It should be recognized that the foregoing description has been limitedto one specific embodiment of the invention. It will be apparent,however, from the description that it can be practiced using othercomponents and with other arrangement than the one that has beendescribed. For example, one need not always employ cannula 30 as theconduit for introducing solution to the surgical site and/or cannula 32as the conduit through which fluid is discharged from the surgical site.Sometimes, the purposes for which cannulae 30 and 32 are employed may bereversed. When cannula 30 is used as the conduit through which fluid isdischarged from the surgical site, the fluid flows up 52 and into bodycenter space 88. The fluid strikes the curved inner wall of body 88 anddevelops a circular flow around the hub frame 58. After flowing throughthe center space 88, the fluid is discharged out of the cannula throughbody opening 84 and hose barb 86. Owing to the curved nature of the flowand the fact that the flow path has an essentially constant crosssectional area, there is again a relatively small pressure drop acrossthis cannula 30 when it is used as a discharge cannula.

It should similarly be understood that, regardless of the direction offluid flow through cannula 32, the pressure drop across this cannula isrelatively low.

Moreover, it should likewise be recognized that the power pack 26 mayhave other energy providing cells than the described batteries 126. Forexample, power pack 26 may include NiCad cells that can be repetitivelyrecharged for multiple uses. Alternatively, the power pack may haverechargeable fuel cells. These cells, once the power in them isdischarged, are recharged by refueling the chemical solution containedtherein with a fresh solution.

It should likewise be recognized that the hand controller 38 and thecontrol circuit 232 may vary from what has been described. Not allcontrollers may include the transducers for measuring fluid flow throughinlet and outlet tubes 28 and 34, respectively, or a transducer formeasuring fluid pressure at the surgical site. Similarly, the power packmonitor circuit 298 for measuring current out of and/or voltage acrossthe power pack may likewise be omitted. Thus, in its most basic form,the control circuit 232 may regulate the energization of the motor basedonly on the depression of buttons 42 and 44.

Similarly, components may be added to the hand controller 38 that aredifferent from the described components. For example, other sensors maybe used to measure fluid flow through the inflow and outflow tubes 28and 34, respectively. Also, a sensor may be provided to monitor theopen/close state of fluid control valve 46. In many preferred versionsof this invention, this sensor is a variable resistor hat functions asthe mounting boss 239. The wiper of this resistor is connected to andset by the rotation of the valve body 234. Alternatively, this sensorcould consist of a Hall effect sensor that generates a signal based onthe relative position of a magnet mounted in valve body 234. The signalproduced by this sensor is applied to the main controller 290. The maincontroller 290 in turn, regulates the energization of the pump based onthe signal representative of the state of the valve. For example, shouldthis signal indicate that degree to which the valve 46 is opened isincreased, motor controller 290 will cause the power to the pump toincrease in order to maintain fluid pressure.

Alternatively displays may be built into more advance versions of handcontroller 38. These displays can provide information regarding thefluid flow rates to and from the surgical site and/or an indication offluid pressure.

Moreover, in some versions of the invention, control circuit 232 mayregulate the open/closed state of the valve. In these versions of theinvention, the valve body, or a bushing around the valve, may be formedfrom material having a very low coefficient of friction such as theTeflon. Also in these versions of the invention, one or more magnets areintegrally mounted in the valve body. The portion of chassis 224 inwhich the valve is seated has plural stators that are actuated so as tocause the movement of the magnets. This movement causes the selectedrotation of the valve 46. A stator energization circuit, (notillustrated) under the control of the main controller 290, selectivelyenergizes the stators so as to set the valve in a selected open/closedstate.

In these versions of the invention, the surgeon depresses buttons toregulate the fluid pressure developed at the surgical site. As a resultof the depression of the buttons, the main controller 290 selectivelymodulates the power applied to the motor and the open/closed state ofthe valve 46.

Also, it should be understood that, while for manufacturingefficiencies, it may desirable to place all the components of thecontrol circuit on a single ASIC, that may not always be the case. Insome versions of the invention, the control circuit may include pluralcomponents.

Moreover, in some versions of the invention, the power regulator circuitmay not be integral with the control circuit 232. In these versions ofthe invention, the power control circuit may be located in the powerpack 26 or pump chassis 122. In these versions of the signal, thecontrol signal for regulating the energization signal applied to themotor 124 is generated by the main controller 290 and applied to thepower control circuit over one of the conductors internal to cable 40.An advantage of the version of the invention is that it eliminates theneed to route the power signal applied to the motor through the handcontroller 38. Still another benefit of this version of the invention isthat it reduces the number of circuit components that need to be fittedinto the hand controller 38.

Therefore, it is the object of the appended claims to cover all suchmodifications as come within the true spirit and scope of thisinvention.

What is claimed is:
 1. A fluid management pump system for supplyingfluid from a container to a surgical site, said system comprising:anelectrically actuated pump to which fluid from the container issupplied, said pump having an outlet conduit and being configured toforce fluid flowed from the container through the outlet conduit; aportable power pack connected to said pump for supplying electricalenergy to said pump; an inflow tube connected to the pump outletconduit, said inflow tube serving as a conduit over which the fluiddischarged from the pump is flowed to the surgical site; a cable havingfirst and second ends, the first end of the cable being connected tosaid pump and said power pack, said cable having wires connected to saidpump and said power pack over which signals for regulating theenergization of the pump are carried and said cable being attached tosaid inflow tube; an outflow tube through which fluid discharged fromthe surgical site is drained from the surgical site, said outflow tubebeing attached at least on partial length thereof to said inflow tube;and a hand controller mounted to said inflow tube and said outflow tube,said hand controller including:a pump control circuit to which thesecond end of said cable is connected, said pump control circuit havinga used actuated switch for regulating said pump and being configured togenerate the signals for regulating the energization of the pump basedon the actuation of said switch; and an adjustable flow control valvefor regulating fluid flow through said outflow tube.